Converter



J. WALKER Jan. 21, 1958 CONVERTER Filed June 7, 1954 .IN V EN TOR.

United States Patent O CONVERTER John Walker, Walnut Creek, Calif., assignor to Henry Kaiser Company, Oakland, Calif., a corporation of evada Application June 7, 1954, Serial No. 434,758

16 Claims. (Cl. 75-60) This invention relates to vessels or converters used in the steel making industry in which molten pig iron from a blast furnace is refined by a modification of the wellknown Bessemer process.

Briefly stated the conventional Bessemer process comprises the pouring of blast furnace metal into a converter which is inclined to one side. The vessel, when charged, is turned into an upright position and atmospheric air is forced through openings in the bottom. The oxygen of the air, as it is forced through the molten mass of metal, burns out most of the silicon, manganese, carbon and other impurities. To the purified iron are added predetermined proportions of carbon, manganese and other such elements depending upon the characteristics of the steel required.

The conventional converter vessel has been described as a pear-shaped container, it is mounted on trunnions which are journaled in pedestals flanking the vessel, and, by means of suitable mechanism, it can be maintained in an upright position or can be rotated for the purpose of receiving a charge of molten iron. Further rotation of the vessel brings it into a position enabling the contents to flow by gravity from the opening, leaving the converter ready for the next charge.

The enlarged metal holding portion of the vessel is conventionally of cylindrical construction having a horizontal transverse section substantially circular in form, this being a logical design from the standpoint of strength and ease of refractory lining installation. The aforementioned openings, or tuyeres in the bottom of the vessel, being uniformly spaced across the entire extent thereof, do not influence the shape of the vessel as described, the individual air streams moving up through the molten metal in what would be, in the absence of the resultant agitation and turbulence, a series of parallel and uniformly spaced currents. In other words, regardless of the shape of the vessel in horizontal section, uniform distribution of the air through the metal can be effected by correct spacing of the tuyeres, this resulting in a condition of substantially complete and even refinement of the iron without any localized over-oxidation.

While the above-described process has been practiced successfully for a century more or less, the comparatively recent adoption of the use of relatively pure oxygen in place of atmospheric air has introduced a number of complications not encountered in the conventional Bessemer process. Attempts to force oxygen through the bottom of the vessel in the usual manner have met with failure due to the fact that tuyeres of the type heretofore used quickly become choked and rendered unserviceable because of the more localized reactions with consequent higher heat generation.

The presently accepted method of bringing oxygen into contact with the hot metal in the vessel is by means of a relatively long pipe or lance which is inserted vertically through the charging opening of the vessel, and through which oxygen is delivered at high velocity to impinge upon the surface of the molten mass. `This high y Velocity impingement, which is necessary to pierce the ICC layer of slag on the surface of the charge, causes a socalled hot spot or highly localized area of contact between oxygen and metal. Gxidation reactions take place at a relatively fast rate, the result being that there is a decided lack of uniformity of refinement throughout the charge and an increased and undesirable oxidation of the iron of the bath.

Attempts have been made to eliminate the highly localized reactions by movement of the lance during the blowing period; however, this involves a continuous removal of slag in order to effect an intimate contact between oxygen and metal and creates the further problem of having to provide and maintain lance actuating mechanism under adverse operating conditions. Various experiments have also been conducted in order to determine the most favorable relationships between vessel capacity, surface area of bath, and depth of molten metal charge, on the basis that certain proportions favorably affect the natural turbulence of the bath reactions and promote a circulation of the metal into and away from the area of oxygen impingement.

lt is the principal object of the present invention to provide a converter which will ensure controlled circulation of the molten metal charge.

Another object of the invention is the provision of a converter having an inside wall surface area better pro portioned relative to the molten metal charge.

Itis a further object of the present invention to provide a lance of improved design to promote favorable circulation of a metal charge in a surface blown converter.

It is yet another object of the present invention to provide a mode of circulation for a molten metal charge in a surface blown converter whereby erosion of the refractory lining of the converter is minimized.

These and other advantages will become apparent during the course of the following description and appended claims, taken in connection with the accompanying drawing forming a part hereof.

In the drawings:

Figure l is a vertical transverse section or" an embodiment of the invention taken on line 1-1 of Figure 2.

Figure 2 is a horizontal transverse section taken on line 2-2 of Figure l.

Figure 3 is a fragmentary vertical section as seen from vline 3 3 of Figure 2.

Figure 4 shows the lower end of a modified form of lance.

Referring to the drawings in detail, a converter vessel shell 10 having the usual trunnions 11 for pivotal mounting, is provided with a refractory lining i?. on the interior walls thereof. The lower part of the vessel as shown on Figure 1 is constructed with confronting walls in generally parallel relationship which, in the upper portion,

.converge and terminate to form the rim of the throat or charging opening 13 of the vessel in the usual manner. As indicated on the section of Figure 2, the lower portion of the vessel has its opposite interior walls in parallel relation to form a quadrilateral having rounded corners 14, the corner radii being kept at a minimum consistent with good refractory lining practice. The upper portion of the. vessel can be constructed to form a transition to the circular throat or opening 13 or such other opening as may be desired.

The bottom of the vessel -as shown on Figure 1 is of double arcuate and unicostate configuration, the arcuate portions thereof being substantially equal and having such relative dimensions and central lines of origin as to generate cylinders 15 which are horizontally coplanar, tangent to the sides of the vessel and tangent to each other- Parallel channels 16 are formed by the aforesaidv Samar 3, shipto the cylinders 15. The height of the ridge o r rib 17 will be such as to form a dividing vane adapted to separate and divert the downwardly owing currents of metal .which are centrally disposed.and,insubstantiahvertical alignment therewith.

In the disclosed embodiment ofthe inventionthexexterior converter shell has been'findicated as lgenerally following the conguraton of. the Vinterior'sides of 'the inner refractory lining 12, and while this is desirable from a standpoint of uniform thickness of vessel insulation, it should be apparent that such .arrangement is, not essential to the practice of the invention.

An encircling ring land upper .and lowerrribs-r19fand 20, respectively, have been providedby .waylof example to ensure adequate rigidity oftheshell 10..

The oxygen lance y21, foruse-imconjunction wththe improved converter,` isY provided :with a f flaredgdischarge end l22 arranged and adapted, to emit .a ,fan-shaped jet ol oxygen'or oxygen enriched air of fresu'icted thickness in the dimension'thereof` .perpendicular toridge 17,- said jet further being of diverging formand to. extend irueach direction along and be in vertical'alignment'withV the longitudinal dimension Vof centrally. disposed. ridge 17 of the bottom of the converter vessel.

Figure 4 presents a Ar'noditied forrnzoffflance 23', of bifurcated design, havingudischarge ends 2li-.Lof reduced transverse dimension to provide .two fan-shapedjets longitudinally arranged in .vertical alignmentv with yridge. 17 of the converter vessel when saidlance .23isoperationally positioned.

As stated heretofore,.the object-of `the-present rinvention. is. to secure a.controlledxcirculation. of kthe molten mass 'of metal in-theconverter vessel during'the rening process. This. result is accomplished by means lof the novel` `forml of converter described combination with the oxygen lance especiallyadapted to cooperate in the im'- proved circulating action. Referringk to'Figure lof v,the drawing, it will be noted that the-bodyof .moltenA metal has in etect been divided into two equal parts symmetrically disposed on either side of armedian vertical plane bisecting the rib or dividing vane 17.I It will be further noted that. with reference to Figure 2, this Acondition is typical for any vertical section taken perpendicular to the rib 17 between the tangent points of the corner radii l141 and the parallel, interior walls 12'throufgh which the section of Figure l is cut. As stated previously, the corner radii 14 will be held to a minimum, the general result being that the section as shown on'Figure l can be considered as being representative of the interior throughout the width of the improved converter vessel in the direction of the rib 17.

During the relining process, the relatively thin and elongated blast or jet of oxygen impinging upon'thefsurface of the bath will cause a downward low of the metal toward and inalignment with the dividing vane 17. This reaction will be given an added impetus as-the gases lof oxidation are formed and the ltwo masses of metal disposed on either side ofthe center rib will be caused t0 rotate within the parallel channels 16 in the manner'iof rollers outlined generally by the circles 15, as shown;

The depth of the molten metal bathis such that the surface of the metal is substantially tangent to the circles 15 with the two bodies'of molten metal circulating-.as described, Without any unbalanced mass of material being displaced, as the metal moving downwardly in the center of the vessel and being .divided and diverted by the action of the rib 17 is counter-balanced by the weight o f the metal near the outer walls of the vessel as it is forced upwardly and inwardly toward the reaction zone.

While the entire charge is, in effecbcirculatingin two `a metal lancearrangedjto deliver a uid in. thespace distinguishable portions, further secondary circulation A,of

the metal within each of these twomasses occurs because of the reactions ofV the oxygen combining with theelements being purged. in 4the.' refining g process.v v

By the disclosed arrangement, Vall ofgthernetalimthe bath will be brought into contact with the oxygen blast from the lance, resulting in a uniformity and completeness oi' refining action not possible in a vessel of conventional shape.

Due to the general cylindrical shape of the rotating' masses of molten metal, circulation of the metal bath as described is achieved, the reactions from the jet impingement and reactions generated in'the circulation zones being adequate to accomplish this result. In order to bring ab'outfa; comparable-circulation in a conventional vto volume of metal, the less will bethe heat concentration on the .refractoryliningperunit area. In a converter designed ,intaccordanceswith.the present invention, it-will be seenfthat .considerable .advantage is` obtained in that the metal-.containing,portionof theV converter in horizontal transversesection lprovidesa periphery which is in excess of three,,andoneehalftirnes,the shortest distance between two opposite walls offtheconverter.

It will be readily understood that lances 21 and 23.

may be operationally water-cooled, as desired, such as .by providing in surrounding relation therewith reverse flow `coolantyjacltets yin -a;,manner. generally known to theart.

While. apreferred embodiment of the invention has been disclosed in detail, it is tobe understood that various `m-odilcations may be madey/ithinthe spirit and scope o the,.. appended claims...

What Vis claimedV is;

l. Thecombination.ofarnetal rening convertercomprisinga hollow vessel'having'an opening atthe upper end thereof, a pair of substantially tlat, confrontinginteriorwalls spaced apart in ythelower part of saidvvessel, and, a. pipeadapted Yto-emit a lluid in the space intermediate said.wallssaid,pipe having an elongated discharge-outlet, the majorfaxis of 1 said'toutlet being parallel t9.. Said walls 2,. A;,metal reiining.;interna1ly blown `converter comprising. athllow Kvessel..has/ing. an @ruining at the .upper endjithereof,V agmetalfcoutaining :portion in Vthe lowerrpart Oftsaidwesseh. said metal-containing' portion havingga minimum i depth;` adjacent .two opposite .substantially iiat Vsides. of saidyessel and ,increasing in depth inwardly Vhaving -a convex dividingy rib protruding upwardly: from said bottom, said rib being located intermediate of and parallel to said first-mentionedl pair of walls' and extending between' said 'second-mentioned pair of walls.

4.v A metal. refining vconverter-*apparatus comprisinga converterV 1Ccordingto clain1. 3,` and'further comprising intermediatefsaidfwalls, ,said lance ,having .a horizonttilly elongated discharge outlet, Ythe major axis` of saidV `outlet beingfa-rranged substantially vertically. Parallel' to said convelltr..bottorndvidirig rib;

5. A metal refining converter apparatus according to claim 4, wherein said lance is provided with a plurality of discharge openings, each of said openings having an elongated discharge outlet, the major axis of each of said outlets being substantially parallel to and vertically arranged with respect to said converter bottom dividing rib.

6. A metal refining converter apparatus comprising a hollow vessel having an opening at the upper end thereof, and a molten metal-containing lower portion comprising a rst pair of substantially flat walls in the interior of said vessel arranged in confronting, substantially parallel relation, a second pair of substantially flat confronting walls arranged substantially perpendicular to and connecting said rst pair of walls at the ends thereof, and a lance adapted to emit a lluid in the space intermediate said walls and against the surface of molten metal in said vessel, said lance having an elongated discharge outlet, the major axis of said outlet being substantially parallel to said molten metal surface and said first-mentioned pair of walls.

7. A metal refining converter comprising a hollow vessel having an interior curvilinear bottom with two concave arcuate portions and an intermediate upstanding convex arcuate rib, and a gaseous fluid feed pipe positioned above said rib.

8. A metal refining converter comprising a refractory lined hollow vessel, the bottom of the refractory lining being curvilinear and having an interiorly arranged upstanding convex arcuate rib, and two concave arcuate portions separated by said rib, and a gaseous fluid feed pipe positioned above said rib.

9. A metal refining converter comprising a hollow vessel having an Opening at the upper end thereof, a curvilinear bottom in said vessel having two concave arcuate portions extending from one wall to the opposing wall in the interior of the vessel, and a centrally located convex rib protruding upwardly on said bottom and extending from said one wall to said opposing wall intermediate said concave portions, and a gaseous uid feed pipe positioned above said rib.

10. A metal refining internally blown converter comprising a refractory lined hollow vessel, a metal-containing section in the lower part of said vessel, the bottom of said metal-containing section being curvilinear and comprising two symmetrically concave arcuate portions such that cylinders generated on the radii of said arcuate portions have substantially horizontally coplanar axes and are mutually tangent and the upper part of said metalcontaining section is substantially tangent thereto and a convex rib on said bottom protruding upwardly into said metal-containing section intermediate said concave arcuate portions.

11. A metal refming internally blown converter comprising a hollow vessel having an opening at the upper end thereof, a metal-containing section in the lower part of said vessel, a substantially at interior wall in the metal-containing section, a second substantially flat interior wall in spaced opposing and substantially parallel relationship with said first-mentioned wall in said metalcontaining section, a curvilinear interior bottom in the metal-containing section connecting Said walls, said bottom having two concave arcuate portions separated by a convex dividing rib protruding upwardly in said bottom and parallel to said walls.

12. A metal rening internally blown converter according to claim 11 having a second pair of substantially flat, opposing and parallel walls connecting said rst-mentioned at walls at the ends thereof providing a metalcontaining section of quadrilateral transverse cross-section.

13. The combination according to claim 1 in which the pipe is provided with a plurality of spaced elongated discharge outlets, the major axes of said outlets being parallel to said walls.

14. The combination of a metal reiining converter comprising a hollow vessel, said vessel having a molten metal-containing Section in the lower part thereof of substantially quadrilateral transverse cross section, said section provided with a bottom having a centrally disposed interior rib, and a lance for delivery of a jet of uid treating agent positioned centrally within said vessel and above said molten metal-containing section, said lance having a narrow elongated discharge outlet, the major axis of said outlet being positioned substantially vertically parallel to said rib.

l5. A method of refining molten metal comprising con- :iining a mass of molten metal in a refining zone having a substantially uniform transverse cross-sectional area, introducing an elongated jet of oxidizing gas along the center line of said mass of molten metal parallel to one transverse dimension of said zone, said mass of molten metal having a reduced depth at the center line thereof and two depth maxima substantially equidistant from said center line, said elongated blast dividing said mass into two symmetrical bodies of metal rotating in opposite directions to facilitate refining of said mass.

16. The combination of a metal refining converter comprising a hollow vessel having an opening at the upper end whereof, a rnetalcontaining section in the lower part of said vessel, a pair of substantially at, parallel opposing interior walls in said metal-containing section, an in terior bottom in said metal-containing section connecting said pair of walls having two concave arcuate portions and an intermediate convex upstanding rib therebetween, and a gaseous fluid feed pipe positioned above said rib, said pipe having an elongated discharge outlet extending in the direction of said rib and substantially parallel to said pair of Walls.

References Cited in the file of this patent UNITED STATES PATENTS 739,340 Orbison Sept. 22, 1903 927,449 Carnahan July 6, 1909 1,463,228 Sauveur July 3l, 1923 2,655,408 Williams Oct. 13, 1953 2,674,210 Holub et al. Apr. 6, 1954 FOREIGN PATENTS 35,906 Germany July 14, 1886 

1. THE COMBINATION OF A METAL REFINING CONVERTER COMPRISING A HOLLOW VESSEL HAVING AN OPENING AT THE UPPER END THEREOF, A PAIR OF SUBSTANTIALLY FLAT, CONFRONTING INTERIOR WALLS, SPACED APART IN THE LOWER PART OF SAID VESSEL, AND A PIPE ADAPTED TO EMIT A FLUID IN THE SPACE INTERMEDIATE SAID WALLS, SAID PIPE HAVING AN ELONGATED DISCHARGE OUTLET, THE MAJOR AXIS OF SAID OUTLET BEING PARALLEL TO SAID WALLS. 